do you mean breakeven in construction or in operating cost ?
breakeven is one thing, but considering nuclear propulsion don't need fuel and can stay almost indefinitely at sea is a big plus for strategic point of view
AFAIK it's overall cost including operation, but even nuclear ships need to come home to port, or you'll end up like the Ural.
Effectively PLAN is already a 5 tier navy, considering the 054A production has been continuing until recently. They do not need another layer between their existing surface combatants. Maybe later they would introduce an even higher layer. I see even that speculative
I mean there is only the 055, 052, 054 and 056, Cute Orca seems to find the need for a theatre air defense cruiser. 052Ds are probably going to be replaced by a ~10kt general purpose destroyer and 054s are getting replaced by some kind of new large frigate, 056s are just good enough and I don't think there is any plans to replace them yet. 055 is tricky, some people think it's successor might be a large BMD cruiser and some others think it'll be a separate role between a air defense cruiser and large general purpose destroyer.